With the urgent shortage of forest resource in China, using agro-residues as raw materials of composite become increasingly important. Agro-residue is the most potential fiber resource, which is helpful to sustainable...With the urgent shortage of forest resource in China, using agro-residues as raw materials of composite become increasingly important. Agro-residue is the most potential fiber resource, which is helpful to sustainable development of composite industries in China. Based on a great deal of researches, this paper summarized and discussed some problems in using agro-residues as raw materials of composites, including raw material preparation, hot-pressing, bonding technology, preventing composite from going moldy. It is proposed that to manufacture the composite of rice straws or wheat straws, the isocayante resin is a suitable adhesive, and the appropriate technologies, bonding, and treatment measures are also needed.展开更多
The polymerization of n-hexyl isocyanate(HNCO) was carried out in the presence of a novel single initiator, rare earth tris(2,6-di-tert-butyl-4-methylphenolate)[Ln(OAr)_3]. The influences of reaction conditions such a...The polymerization of n-hexyl isocyanate(HNCO) was carried out in the presence of a novel single initiator, rare earth tris(2,6-di-tert-butyl-4-methylphenolate)[Ln(OAr)_3]. The influences of reaction conditions such as the monomer concentration, the polymerization temperature and time, and the types of solvents on the polymerization of HNCO were studied. Polymerizations of phenyl, i-propyl, p-tolyl, n-butyl and n-octyl isocyanates with La(OAr)_3 were also examined.展开更多
Phenyl isocyanate was for the first time successfully polymerized by divalent samarium complex (ArO)2Sm(THF)4. The monomer concentration and temperatur affected the polymerization greatly.
The uncatalyzed reaction of p-tolyl isocyanate(p-TI)with water in N,N-dimethylformamide(DMF)was investigated by high performance liquid chromatography(HPLC).The reactions were carried out at different temperatures fro...The uncatalyzed reaction of p-tolyl isocyanate(p-TI)with water in N,N-dimethylformamide(DMF)was investigated by high performance liquid chromatography(HPLC).The reactions were carried out at different temperatures from 293 K to 323 K,using various molar ratios of water to p-TI.DMF,as a special amide,was proved to be an efficient catalyst for water–isocyanate reaction.Under the reaction conditions in this study,substituted urea was the only final product observed.An appreciable amount of intermediate p-toluidine was detected.Concentrations of the isocyanate group as well as the amine and urea were determined as a function of time.New kinetic equations were deduced for each of the substance on the basis of a multistep mechanism,instead of a simple second order reaction as usual.Kinetic constants were calculated using the software MATLAB.Furthermore,the effects of temperature and concentrations of reactants on the reaction rate and amine content were discussed.The activation energy of each step was also determined.展开更多
The oligomerization of phenyl isocyanate catalyzed by divalent his (methylcyclopentadienyl)samarium complex was studied. The initiating reaction and the effect of coordination environment around the samarium atom were...The oligomerization of phenyl isocyanate catalyzed by divalent his (methylcyclopentadienyl)samarium complex was studied. The initiating reaction and the effect of coordination environment around the samarium atom were mainly discussed. It is found that the initiation reaction has a great influence on the apparent catalytic activity. The oligomers can be split into two fractions. The methanol insoluble fraction is mainly composed of dimers, while the methanol soluble fraction is mainly composed of trimers. Neither SmI2 nor SmI2(hmpa)(4)(hmpa = hexamethylphosphoric triamide) shows catalytic activity for the oligomerization of phenyl isocyanate.展开更多
A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate wi...A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.展开更多
Bis （methylcyclopentadienyl） lanthanide amido complex （MeCp） 2YbNPh2 （THF） reacted with n-hexyl isocyanate （n-nexylNCO） in 1：1 molar ratio to give {（MeC5H4）2Yb[OC（NPh2）N（n-hexyl）] }2（1）. Complex 1 was...Bis （methylcyclopentadienyl） lanthanide amido complex （MeCp） 2YbNPh2 （THF） reacted with n-hexyl isocyanate （n-nexylNCO） in 1：1 molar ratio to give {（MeC5H4）2Yb[OC（NPh2）N（n-hexyl）] }2（1）. Complex 1 was characterized by elemental analyses and X-ray diffraction. The title complex belongs to trigonal system and R-3 space group. Its unit cell parameters are a =2.9533（11） nm, b =2.9533（11） nm, c = 1.5873（6） nm, V= 11.9896（80） nm^3, Z =9, Dc= 1.562 mg·m^-3, μ = 3.536 mm^-1（Mo Kα）, F（000） =5670, R =0.034, Rw =0.064. It is a dimeric structure with two symmetrical bridged oxygen atoms. Nitrogen atom is coordinated to the ytterbium atom to form a tricyclic backbone. The coordination number of ytterbium is 9. The whole molecule shows central symmetry.展开更多
Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield subs...Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield substituted urea.展开更多
Subcutaneous administration of methyl isocyanate (MIC) in 0.5 LDso and 1.0 LD50 to female rabbits resulted in significant increases of hemoglobin concentration, hematocrit and leukocyte count in blood, as well as plas...Subcutaneous administration of methyl isocyanate (MIC) in 0.5 LDso and 1.0 LD50 to female rabbits resulted in significant increases of hemoglobin concentration, hematocrit and leukocyte count in blood, as well as plasma total proteins, urea and cholesterol. A significant decrease in plasma albumin level was only observed in the 1.0 LD50 group. Urine of MIC intoxicated animals showed presence of protein, bilirubin, elevated urea and urobilinogen, while urine volume was reduced. The hematological and biochemical changes induced by MIC are perhaps the result of fluid loss from the vascular compartment as evidenced by the histopathological observations. This study further substantiates the view that acute toxicity of MIC is mediated in vivo by its effects on vascular beds.展开更多
The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers （ITPE） was investigated. The progress of the reaction and the structural changes during modification process wer...The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers （ITPE） was investigated. The progress of the reaction and the structural changes during modification process were studied using FTIR spectroscopy. The studies support the proposition that TDI （tolylene diisocyanate） acts as a coupling agent between the epoxy and polyethers, forming a urethane linkage with the former and the latter, respectively. Me THPA-cured ER/ITPs blends were characterized using dynamic mechanical analysis （DMA） and thermogravimetric analysis （TGA）. It is indicated the glass transition temperature （T） of systems was lower than the T of pure epoxy resin and overfull ITPE separated from the modified epoxy resin and formed another phase at an ITPE-content of more than 10wt%. The thermal stability was decreased by the introduction of ITPE. The impact strength and the flexural strength of the cured modifiedepoxy increased with increasing the ITPE content and a maximum plateau value of about 24.03 kJ/m^2 and 130.56 MPa was measured in 10wt% ITPE. From scanning electron microscopy （SEM） studies of the fractrue surfaces of ER/ITPE systems, the nature of the micromechanisms responsible for the increases in toughness of the systems was identified.展开更多
文摘With the urgent shortage of forest resource in China, using agro-residues as raw materials of composite become increasingly important. Agro-residue is the most potential fiber resource, which is helpful to sustainable development of composite industries in China. Based on a great deal of researches, this paper summarized and discussed some problems in using agro-residues as raw materials of composites, including raw material preparation, hot-pressing, bonding technology, preventing composite from going moldy. It is proposed that to manufacture the composite of rice straws or wheat straws, the isocayante resin is a suitable adhesive, and the appropriate technologies, bonding, and treatment measures are also needed.
文摘The polymerization of n-hexyl isocyanate(HNCO) was carried out in the presence of a novel single initiator, rare earth tris(2,6-di-tert-butyl-4-methylphenolate)[Ln(OAr)_3]. The influences of reaction conditions such as the monomer concentration, the polymerization temperature and time, and the types of solvents on the polymerization of HNCO were studied. Polymerizations of phenyl, i-propyl, p-tolyl, n-butyl and n-octyl isocyanates with La(OAr)_3 were also examined.
文摘Phenyl isocyanate was for the first time successfully polymerized by divalent samarium complex (ArO)2Sm(THF)4. The monomer concentration and temperatur affected the polymerization greatly.
基金Supported by the Key Science and Technology Innovation Team of Zhejiang Province(2011R50007)
文摘The uncatalyzed reaction of p-tolyl isocyanate(p-TI)with water in N,N-dimethylformamide(DMF)was investigated by high performance liquid chromatography(HPLC).The reactions were carried out at different temperatures from 293 K to 323 K,using various molar ratios of water to p-TI.DMF,as a special amide,was proved to be an efficient catalyst for water–isocyanate reaction.Under the reaction conditions in this study,substituted urea was the only final product observed.An appreciable amount of intermediate p-toluidine was detected.Concentrations of the isocyanate group as well as the amine and urea were determined as a function of time.New kinetic equations were deduced for each of the substance on the basis of a multistep mechanism,instead of a simple second order reaction as usual.Kinetic constants were calculated using the software MATLAB.Furthermore,the effects of temperature and concentrations of reactants on the reaction rate and amine content were discussed.The activation energy of each step was also determined.
文摘The oligomerization of phenyl isocyanate catalyzed by divalent his (methylcyclopentadienyl)samarium complex was studied. The initiating reaction and the effect of coordination environment around the samarium atom were mainly discussed. It is found that the initiation reaction has a great influence on the apparent catalytic activity. The oligomers can be split into two fractions. The methanol insoluble fraction is mainly composed of dimers, while the methanol soluble fraction is mainly composed of trimers. Neither SmI2 nor SmI2(hmpa)(4)(hmpa = hexamethylphosphoric triamide) shows catalytic activity for the oligomerization of phenyl isocyanate.
基金Funded by the National Natural Science Foundation of China(Nos.21244006 and 50873013)the Beijing Natural Science Foundation(No.2182056)
文摘A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.
文摘Bis （methylcyclopentadienyl） lanthanide amido complex （MeCp） 2YbNPh2 （THF） reacted with n-hexyl isocyanate （n-nexylNCO） in 1：1 molar ratio to give {（MeC5H4）2Yb[OC（NPh2）N（n-hexyl）] }2（1）. Complex 1 was characterized by elemental analyses and X-ray diffraction. The title complex belongs to trigonal system and R-3 space group. Its unit cell parameters are a =2.9533（11） nm, b =2.9533（11） nm, c = 1.5873（6） nm, V= 11.9896（80） nm^3, Z =9, Dc= 1.562 mg·m^-3, μ = 3.536 mm^-1（Mo Kα）, F（000） =5670, R =0.034, Rw =0.064. It is a dimeric structure with two symmetrical bridged oxygen atoms. Nitrogen atom is coordinated to the ytterbium atom to form a tricyclic backbone. The coordination number of ytterbium is 9. The whole molecule shows central symmetry.
文摘Low-valent titanium reagent prepared from titanium tetrachloride and zinc was empolyed to induce the coupling reaction of thiocyanates with tetrahydrofuran yield alkyl 4-hydroxy butyl sulfide and isocyanate yield substituted urea.
文摘Subcutaneous administration of methyl isocyanate (MIC) in 0.5 LDso and 1.0 LD50 to female rabbits resulted in significant increases of hemoglobin concentration, hematocrit and leukocyte count in blood, as well as plasma total proteins, urea and cholesterol. A significant decrease in plasma albumin level was only observed in the 1.0 LD50 group. Urine of MIC intoxicated animals showed presence of protein, bilirubin, elevated urea and urobilinogen, while urine volume was reduced. The hematological and biochemical changes induced by MIC are perhaps the result of fluid loss from the vascular compartment as evidenced by the histopathological observations. This study further substantiates the view that acute toxicity of MIC is mediated in vivo by its effects on vascular beds.
基金the Natural Science Foundation of Hubei Province (No.2006ABA321)
文摘The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers （ITPE） was investigated. The progress of the reaction and the structural changes during modification process were studied using FTIR spectroscopy. The studies support the proposition that TDI （tolylene diisocyanate） acts as a coupling agent between the epoxy and polyethers, forming a urethane linkage with the former and the latter, respectively. Me THPA-cured ER/ITPs blends were characterized using dynamic mechanical analysis （DMA） and thermogravimetric analysis （TGA）. It is indicated the glass transition temperature （T） of systems was lower than the T of pure epoxy resin and overfull ITPE separated from the modified epoxy resin and formed another phase at an ITPE-content of more than 10wt%. The thermal stability was decreased by the introduction of ITPE. The impact strength and the flexural strength of the cured modifiedepoxy increased with increasing the ITPE content and a maximum plateau value of about 24.03 kJ/m^2 and 130.56 MPa was measured in 10wt% ITPE. From scanning electron microscopy （SEM） studies of the fractrue surfaces of ER/ITPE systems, the nature of the micromechanisms responsible for the increases in toughness of the systems was identified.
